Identification of two mechanisms for current production in a biharmonic flashing electron ratchet

What is it about?

A theoretical study exploring the effect the shape of the applied potential has on the current obtained in an electron ratchet. Typically, both theory and experiments in the ratchet field use a simple sawtooth shape, either a piecewise linear (sharp sawtooth), or a biharmonic (sum of two sine waves) with a specific set of pre-factors. But how sensitive is the performance to the shape itself? What if instead of one asymmetric shape, we choose another, slightly different one? Here, we used quantum-mechanical simulations of an electron ratchet; we varied the shape of the potential, as well as the damping strength in the system. We identified two different ratcheting mechanisms, at low and high damping regimes, and found that the ratchet current is extremely sensitive to the shape of the potential – a small change of the shape can result in a nullification or even a reversal of the current. Current reversals are the most puzzling property of ratchet, and in this work we provided an intuitive explanation for one class of reversals .

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